1. Field of the Invention
The invention relates to a radiation imaging apparatus which takes radiographic images of a breast of a subject.
2. Description of the Related Art
Conventionally, various modifications of mammography apparatus for taking X-ray fluoroscopic images of mammary glands and/or breasts have been proposed.
For example, Japanese Patent Application Laid-Open No. 2003-116825 discusses a technique for obtaining three-dimensional data and calculating volume data in order to increase an amount of diagnostic data.
Also, Japanese Patent Application Laid-Open No. 2004-105729 discusses a technique for obtaining images including three-dimensional data and calculating volume data without pressing a chest region of a subject.
It is well known that the incidence of breast cancer is high in the vicinity of the axillae. This is a reason for adopting medio-lateral oblique (MLO) as an imaging direction in X-ray mammography. It is possible to take images of axillary portions by using an entire body CT scanner, which is capable of taking tomograms of the entire body of a subject. However, the entire body CT scanner has a disadvantage such that portions irrelevant to the diagnosis are exposed to radiation and the reconstruction area is too large, resulting in an unsatisfactory resolution. That is, the chest CT scanner is required to appropriately scan in the vicinity of axilla. However, conventional techniques fail to satisfy the requirement.
When an excision operation is carried out on a cancer portion of a breast while referring to previously taken CT images, the CT images of a subject have to be taken in a posture similar to the posture under operation (i.e., a supine position). However, conventionally there is no X-ray mammography technique capable of capturing an image in a supine position excluding the entire body CT scanner.